Jeepman Posted January 14, 2015 Share Posted January 14, 2015 The Bosch Injector # 0280155700 is 18.25lbs @43.5psi Which means if your running 44psi they are 18.5 and on the throttle 48psi then they are 19.2lbs I think you could be close to where you should be but since I do not know your stock injector as they were more then one size used and I can not remember the last time I had an OBDI engine to play with and really the best way to get injectors sizing correct is with an A/F gauge... In this case I wouldn't go back to your stock regulator without testing your A/F ratio as you could be too little fuel as it would drop the injectors down to 15.4lbs@31psi and 17.3@39psi... How is the power feel and what is your fuel economy like as the wrong injectors will rob you of power and or rob your wallet to pay for fuel... Link to comment Share on other sites More sharing options...
ggcnash Posted January 14, 2015 Share Posted January 14, 2015 I would also like to know how it is running! The only time I've heard of people using bigger injectors and higher pressure is for modified engines. My buddy is running your same injectors and regulator on a poormans stroker. I personally can't imagine it running better with a stock engine ,but heck what do I know learn something on here just about everyday! Just FYI my upgraded injectors with stock regulator Bosch 0280155703 good luck! Link to comment Share on other sites More sharing options...
Jeepman Posted January 14, 2015 Author Share Posted January 14, 2015 I would also like to know how it is running! The only time I've heard of people using bigger injectors and higher pressure is for modified engines. My buddy is running your same injectors and regulator on a poormans stroker. I personally can't imagine it running better with a stock engine ,but heck what do I know learn something on here just about everyday! Just FYI my upgraded injectors with stock regulator Bosch 0280155703 good luck! which is why I see people over look the injectors more then anything else I think... Your 703's are 16.75lbs@43.5psi which is 14.1bs@31psi and 15.9lbs@39psi which I think is too low but that really depends on your truck and other mods to your truck... In my experience the OE injectors are undersized from the factory to run lean which adds more power and better fuel economy but the adverse effect is the manifolds crack due to the lean conditions and you can verify this yourself if need be... running a little rich is safer for the engine but will cost you a little more in fuel... Link to comment Share on other sites More sharing options...
ggcnash Posted January 14, 2015 Share Posted January 14, 2015 I would also like to know how it is running! The only time I've heard of people using bigger injectors and higher pressure is for modified engines. My buddy is running your same injectors and regulator on a poormans stroker. I personally can't imagine it running better with a stock engine ,but heck what do I know learn something on here just about everyday! Just FYI my upgraded injectors with stock regulator Bosch 0280155703 good luck! which is why I see people over look the injectors more then anything else I think... Your 703's are 16.75lbs@43.5psi which is 14.1bs@31psi and 15.9lbs@39psi which I think is too low but that really depends on your truck and other mods to your truck... In my experience the OE injectors are undersized from the factory to run lean which adds more power and better fuel economy but the adverse effect is the manifolds crack due to the lean conditions and you can verify this yourself if need be... running a little rich is safer for the engine but will cost you a little more in fuel... In no way am I doubting you Jeepman just interested in his findings. My truck is stock besides k&n cai and injectors and of course exhaust. The 703's run great they added throttle response and seem to pur a little better at idle, but if there is a better option I'm all for it. Link to comment Share on other sites More sharing options...
Jeepman Posted January 14, 2015 Author Share Posted January 14, 2015 No worries as I am not saying they are wrong for you or anyone else as for that matter, each Jeep is different and as a Stock replacement they are a better option due to the 4 hole nozzle over the 1 hole nozzle... Just that to tune specifically the injector size its best to monitor the A/F ratio and find the best spot for the engine, people do not realize that every little change to the engine can and will have an effect on the performance of the engine so a simple changing the exhaust flow can change the needs of the engine.... By chance you still have your OE injectors? if so find the part number on them and I can see what the stock specs are... Its always good to know what your changing so you know why your getting a better performance or worse performance then OE... When I installed my 4.7L Stroker engine I added an A pillar air fuel gauge so I can monitor my ratios and my first set of injectors I ran worked great for the engine and I was mostly happy with the Power till I decided to swap them for another set I had but couldn't find them so I used my slightly smaller set and found a Huge increase in power and much better A/F ratio... I am by no means done tweeking and testing but if you have the ability to monitor before and after your changes you will have better success with the changes you make... Link to comment Share on other sites More sharing options...
Rohls Posted January 14, 2015 Share Posted January 14, 2015 Thanks JEEPMAN for starting this. To be clear, I followed the chart found in the thread I started (http://comancheclub.com/topic/42856-what-upgrade-fuel-injectors-do-i-purchase-92-40l/) some time ago...it followed the other research i gathered at the time...sorta made sense. Please correct me if I'll way off here. The chart is the following...says it's for STOCK 4.0L...: I have the FORD 710 injectors and Chrysler #4418850 regulator currently, and for the last 6 or so months. My mileage probably increased slightly due to the injectors, but I have done a couple other things that detract. I opened up the exhuast with a 2.5" magnaflow and am running stock gears with 31" tires. Truck is DD. I get 15 MPG around town and 17 MPG on the highway....not bad I suppose....:) The truck is notceably more torquey and responsive because of this...and more fun to drive when it sounds bad-@$$:) I guess I don't understand why I would want to step back down to a stock FPR ( which limits to 39PSI) when my injectors (FORD 710) are made to perform 18/19 lb/hr @ 44/49 PSI...? In fact I most likely did this when I was going through all of this....I swapped the injectors to the 710s and left the stock FPR in there...==>> It ran like crap. Bumped up to the FPR in the chart above==>> performance as it is today. I'd have to look for the old injectors, but would guess they were stock from the factory...like 20 lbs/hr @ 39PSI...right? So.. I'll keep my set up for now unless I get input from you all... :thumbsup: Back to why I starting poking around.... What else could be causing the 'COLD engine = easy start (like 1 revolution) WARM engine = hard start (like 5 revolutions)" ??? Fuel pump? Regulator? Does my 'Manche have a check valve near the fuel tank/pump...? IIRC I have 0 PSI at the newly installed fuel gauge ( :yes: ) when key-off, that's fine, but after the truck sits for a couple minutes this is also the case...normal? JEEPMAN--What is your A/F gauge like? Easy enough to do...? Thanks again! Link to comment Share on other sites More sharing options...
Jeepman Posted January 15, 2015 Author Share Posted January 15, 2015 I guess I don't understand why I would want to step back down to a stock FPR ( which limits to 39PSI) when my injectors (FORD 710) are made to perform 18/19 lb/hr @ 44/49 PSI...?My first post here I stated its not a good idea to swap back to the stock fuel pressure because these 710 injectors would run too low lbs and the 703 (16.75lbs@43.5psi which is 14-16lbs@31-39psi) slightly smaller then the 710's which is probably why that chart suggests changing the Pressure regulator... Your 710's are 18.25lbs@43.5psi so yes they are basically good for 18-19lbs... The truck is noticeably more torquey and responsive because of this...and more fun to drive when it sounds bad-@$$ :) What it seams like to me is these injectors leaned you out (exactly how much I can not say till we know what your OE injectors were) which is why you felt more power and fuel economy... In fact I most likely did this when I was going through all of this....I swapped the injectors to the 710s and left the stock FPR in there...==>> It ran like crap. Bumped up to the FPR in the chart above==>> performance as it is today. I'd have to look for the old injectors, but would guess they were stock from the factory...like 20 lbs/hr @ 39PSI...right? It ran poorly because you were down to 15.4lbs@31psi and 17.3@39psi and your engine wanted more Fuel... What else could be causing the 'COLD engine = easy start (like 1 revolution) WARM engine = hard start (like 5 revolutions)" ??? Fuel pump? Regulator? Does my 'Manche have a check valve near the fuel tank/pump...? IIRC I have 0 PSI at the newly installed fuel gauge ( :yes: ) when key-off, that's fine, but after the truck sits for a couple minutes this is also the case...normal? Well first thing I would do is see what your rail pressure is when the system primes when cold (without cranking) and check again when Hot... I would be thinking that your IAC is either dirty, not working properly or just not understanding the system and not allowing enough air in after you shut down warm I had a similar issue with my engine when I had my largest injectors in and swapped IAC's 3 times with no change cold it would start and hot I would have to have my foot on the throttle to get it to run... As I changed my injectors the IAC adjusted the idle air better to match my fuel so its not impossible its the IAC but without seeing the truck its only a guess... JEEPMAN--What is your A/F gauge like? Easy enough to do...? My A/F is Great and currently I am running a little rich at WOT (120KPH+) but I still have some tweeking to do still... As for the install it is very easy to do and if you can not weld the 02 bung in you just get a local Muffler shop to drill the hole and weld in the bung then everything else is as simple as mounting the gauge where you want it and adding switched power... Its awesome monitoring device to have in the Jeep, I run an Autometer Phantom as I had a certain look I was after but you can get inexpensive ones at http://www.glowshiftdirect.com/... Link to comment Share on other sites More sharing options...
cruiser54 Posted January 15, 2015 Share Posted January 15, 2015 Stock injectors have plenty of "headroom". The ECU controls them via "duty cycle". The air to fuel ratio is NOT controlled by the injectors, but by inputs to the eCU which are translated into outputs to the injectors. Link to comment Share on other sites More sharing options...
Jeepman Posted January 15, 2015 Author Share Posted January 15, 2015 Not saying the injector directly control the A/F however indirectly they do have an effect on it regardless of the computer, because the computer will always try to get the A/F perfect to 14.7 which it can not do in all conditions especially when the injectors are too large or too small for the application... Example: If the computer could do this just by adjusting the duty cycle there wouldn't be a need for larger or smaller injectors, try installing the incorrect injectors and you will see the ECU will try its best to get the ratio right, but it will not and then you lose power and fuel economy... As for Stock having headroom I assume you mean they have room to grow into which I will disagree with as I believe they are too small from the factory which is why 4.0L's especially run leaner then I like but that's how they were engineered and I believe that's the main reason for manifold cracks as well... This is just MY Personal experiences having worked on and tested several Jeeps and By No means am I declaring my experience is the only one, That's why I have said its best to run an A/F gauge and monitor each application which is what I do it in my business just to make sure because you can crunch the numbers all day long but that never means that's the correct option just a good starting point... Test test and test more, as each vehicle will have different needs as NO 2 Jeeps are built exactly the same... Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 15, 2015 Share Posted January 15, 2015 The simple easy solution to injector sizing for a built HO or even a stock engine is having an A/F meter and an adjustable fuel regulator. Then bring it to your local dyno tester to have them dial it in as to your preferences; economy or best performance to verify. Or experiment on your own with different fuel pressures and monitor the A/F meter to get a good balance - just takes more trial and error time. Then drive it until the ECU "learns" the new settings. Not difficult at all. Unfortunately the Renix computer doesn't learn or compensate, it simply takes inputs from the sensors and goes with what comes in goes out. An A/F meter is mandatory IMO for tuning a Renix since the computer is merely a junction block and doesn't adjust or compensate. Of course I'm not a Renix expert, don't want to be, so correct me if I'm wrong in calling the Renix "ECU" a dumb computer. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 15, 2015 Share Posted January 15, 2015 Not saying the injector directly control the A/F however indirectly they do have an effect on it regardless of the computer, because the computer will always try to get the A/F perfect to 14.7 which it can not do in all conditions especially when the injectors are too large or too small for the application... Example: If the computer could do this just by adjusting the duty cycle there wouldn't be a need for larger or smaller injectors, try installing the incorrect injectors and you will see the ECU will try its best to get the ratio right, but it will not and then you lose power and fuel economy... As for Stock having headroom I assume you mean they have room to grow into which I will disagree with as I believe they are too small from the factory which is why 4.0L's especially run leaner then I like but that's how they were engineered and I believe that's the main reason for manifold cracks as well... This is just MY Personal experiences having worked on and tested several Jeeps and By No means am I declaring my experience is the only one, That's why I have said its best to run an A/F gauge and monitor each application which is what I do it in my business just to make sure because you can crunch the numbers all day long but that never means that's the correct option just a good starting point... Test test and test more, as each vehicle will have different needs as NO 2 Jeeps are built exactly the same... They are not too small and indeed do have more headroom. The Renix runs lean as you call it because of computer control, not injector size. Injectors are sized so the ECU can reduce the duty cycle down small enough to get an idle, but provide enough fuel at WOT. The only reasons to go larger are if you build a stroker or add forced induction. Link to comment Share on other sites More sharing options...
Jeepman Posted January 15, 2015 Author Share Posted January 15, 2015 They are not too small and indeed do have more headroom. The Renix runs lean as you call it because of computer control, not injector size. Injectors are sized so the ECU can reduce the duty cycle down small enough to get an idle, but provide enough fuel at WOT. The only reasons to go larger are if you build a stroker or add forced induction. Lets just Nip this Right Now... I have not and will not speak in absolutes and anyone that does is arrogant to do so, as no two setups are exactly the same so this is not going to be a Pi$$ing contest... Nor am I speaking specifically to a certain setup to pi$$ anyone off... I will Never say "you have to do this or have to that or tell you your wrong" its your Jeep you do what you want I am just giving information and my experience in MY thread... This Thread was for specific Injector information what is done with that information is up to the person who uses that Injector... We can disagree and as said already before In my experience the factory injectors are too small for my ME if they work for you that's great its your Jeep and I do not know it so why would I say your wrong for your application, but if your speaking for everyone else in the world then that's wrong as you do not and will not have hands on every Jeep to truthfully say that... I absolutely detest anyone that tries to tell me either in person or over the internet what works or does not work for my Jeep when they have ZERO knowledge of my Jeep or what I have done to my Jeep or what I am going to do to my Jeep... As I have Said Over and Over Again " You Need to monitor the A/F to get it setup properly to how you want it and it seams to not have been read"... This is My experience with an A/F gauge and actually testing it on Jeeps and even minor changes will cause an effect on the A/F ratio so I do not believe injector swaps are just for strokers and forced induction but again its up to the person to test the A/F ratio's to figure out what's best for them ... Do as you will with the info as I do not want to bicker over personal opinion... The simple easy solution to injector sizing for a built HO or even a stock engine is having an A/F meter and an adjustable fuel regulator. Then bring it to your local dyno tester to have them dial it in as to your preferences; economy or best performance to verify. Or experiment on your own with different fuel pressures and monitor the A/F meter to get a good balance - just takes more trial and error time. Then drive it until the ECU "learns" the new settings. Not difficult at all. Unfortunately the Renix computer doesn't learn or compensate, it simply takes inputs from the sensors and goes with what comes in goes out. An A/F meter is mandatory IMO for tuning a Renix since the computer is merely a junction block and doesn't adjust or compensate. Of course I'm not a Renix expert, don't want to be, so correct me if I'm wrong in calling the Renix "ECU" a dumb computer. Hornbrod has a great option as well for those who either can not do the testing themselves or do not want to... Link to comment Share on other sites More sharing options...
Rohls Posted January 16, 2015 Share Posted January 16, 2015 Thank you for all the info. I will be looking in to getting a A/F gauge and adjustable MAP sensor....let the tinkering continue! :) Link to comment Share on other sites More sharing options...
cruiser54 Posted January 16, 2015 Share Posted January 16, 2015 Just so ya know, I have set up fuel injection systems, not unlike Renix, with forced induction. I do know about injectors, headroom, need for more fuel at WOT etc. I have driven with a boost gauge zip-tied to one wiper blade, a fuel pressure gauge to the other wiper, and had an AFR gauge in the dash. I also know that too large of injectors can sometimes not be trimmed enough by an ECU to pass emissions while they do supply plenty of fuel at WOT. That's why there are piggyback controllers to assist with that. As to the info I provided on the 4.0s, it is accurate. There are plenty of proven plug and play options out there for the crappy Siemens-Deka leak-prone pieces of crap that came with our Comanches. Link to comment Share on other sites More sharing options...
Jeepman Posted January 16, 2015 Author Share Posted January 16, 2015 Cruiser Thanks and I am sure you have great success at it too but You Keep Missing the point to these posts you chose to ignore what I have said or are purposely trying to start a fight however I just refuse to debate with someone when there is No Debate... Of all the sites I belong to this is one I probably enjoy the most and is the only one I donate Money to as it is specific to my truck and like minded people, and I like the normal peace and quite here... Mods please just close the thread or delete it as I am done... Link to comment Share on other sites More sharing options...
cruiser54 Posted January 16, 2015 Share Posted January 16, 2015 In my experience the OE injectors are undersized from the factory to run leanwhich adds more power and better fuel economy but the adverse effect is the manifolds crack due to the lean conditions and you can verify this yourself if need be...running a little rich is safer for the engine but will cost you a little more in fuel... This^^ is what I have an issue with. Hence my responses. They run at 14.7 to 1 in closed loop which happens quite quickly. At WOT, actually about 80% throttle or more, the AFR is not controlled by the O2 sensor anymore. That's open loop. So, the injectors are not undersized to run lean. They're correct for the application and the ECU controls them. The manifolds do not crack due to the air fuel ratio being too lean. It isn't too lean at 14.7 to 1. If the injectors were indeed the cause of cracked manifolds because of their size, that would mean everyone who has a cracked manifold has it because they ran the engine at WOT for extended periods of time with too small of injectors. They cracked because they were of poor design, had no give in the system, and people ran for long times with bad motor mounts. Link to comment Share on other sites More sharing options...
Jeepman Posted January 16, 2015 Author Share Posted January 16, 2015 Stop already Your not Proving anything... My Opinion and experience is just that MINE so enough... You Still DO not understand and YES in my OPINION all the lean system is as said already one of the reasons the manifolds crack and Yes they are a crap design But guess what Borla Headers Crack and So do any other header made and again IN my OPINION its cause the manifolds get too Hot and you add that with the Stiff ride and bumps and bangs of a Jeep suspension and it stretches the metal... Its MY OPINION and You do not have to like it and you can try to bully your way but I am Not one to be bullied as I am No kid who can easily be scared and Have had more then 10 Years Just Working on and Tearing apart just about every model of Jeep ever made... Again Thanks for your Opinion but it was Not asked for Nor Wanted in MY Thread... Again Moderators Please close this thread as I see it becoming a Problem and things are going to get out of hand... Link to comment Share on other sites More sharing options...
HOrnbrod Posted January 16, 2015 Share Posted January 16, 2015 In my experience the OE injectors are undersized from the factory to run lean which adds more power and better fuel economy but the adverse effect is the manifolds crack due to the lean conditions and you can verify this yourself if need be... running a little rich is safer for the engine but will cost you a little more in fuel... This^^ is what I have an issue with. Hence my responses. They run at 14.7 to 1 in closed loop which happens quite quickly. At WOT, actually about 80% throttle or more, the AFR is not controlled by the O2 sensor anymore. That's open loop. So, the injectors are not undersized to run lean. They're correct for the application and the ECU controls them. The manifolds do not crack due to the air fuel ratio being too lean. It isn't too lean at 14.7 to 1. If the injectors were indeed the cause of cracked manifolds because of their size, that would mean everyone who has a cracked manifold has it because they ran the engine at WOT for extended periods of time with too small of injectors. They cracked because they were of poor design, had no give in the system, and people ran for long times with bad motor mounts. Yep. And the vehicle operator is basically clueless what the AFR is w/o an A/F meter to monitor it. I keep mine close to 14.8 to 1, and dial it back in with the adjustable FPR whenever I make changes to the suck and blow systems, including injectors. W/o an A/F meter you're just p!$$ing in the wind. To me an A/F meter is a vital tool for monitoring the overall health of your engine. EDIT: And Jeepman, with all due respect, this is not your thread just because you started it. Once posted it's open for all to agree or disagree. Just because someone disagrees with your opinions isn't valid cause to close the thread. I personally think you are spot on, but that's irrelevant. I also think this thread is a good discussion and beneficial to the majority of CC members. Link to comment Share on other sites More sharing options...
Jeepman Posted January 16, 2015 Author Share Posted January 16, 2015 Hornbrod you are correct. It's not my thread but it's frustrating when the words on the page are not interpreted or misinterpreted. Others oponions are great just not someone speaking as a fact when realistically there are too many variables to be a fact. I will just take myself out of the equation. As they say cooler heads prevail and I thank you for the intervention so to speak. Link to comment Share on other sites More sharing options...
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